Television system



w. H. PECK TELEVISION SYSTEM Filed Sept. 26, 1939 2 Sheets-Sheet 1 INVENTOR.

mLL/AMHPS'CK.

ATTORNEYS July 21, 1942.

July 21, 1942.

w. H. P'ECK 2,290,651.

TELEVIS ION SYSTEM Filed Sept. 26, 1939 2 Sheets-Sheet 2 INVENTOR. Wu. #1 M fiPEc/n ATTORNEYS 7 Patented July-21, 1 942 f TELEVISION SYSTEM William H. Peck, Tarrytown, N. Y.

Application September 26, 1939, Serlal Iva-29 ,546 i 4 1 2 clai s. (or. nix-"2.33

This invention" pertains to improvements in television systems, and more. especially television receiving systems, V

The invention introduces into such systems,

a number of basically new features both-as to mode of operation and as to apparatus employed. Thus, in accordance with one aspect of the invention, line scanning is effected by a newtype of multiple unit Kerr'cell, the individual-cell units of which are successively energized. in accordance with television signals over a relatively small number of leads, sealed through the glass container thereof, by means of a novel switching arrangement employing tively actuated by electronic beam deflection, and hence involving no mechanically moving elements or inertia efifects. The electronic beam referred to is also modulated in accordance with the televisionsignals whereby switching and signal energization of the Kerr cells, are simultaneously eilected by the same apparatus.

In the preferred embodiment, the; electronic switching devices take the form of specially constructed cathode ray tubes in which theele'ctronic cathode ray beam is caused'to repeatedly traverse a plurality of conductive segments disposed about the circular screen thereof and insulated from one another, wherebyswitching is accomplished to segment. The electronic beam is modulated in the usual way by television signals so that its incidenceuppn a given Segment provides the signal intensity for appropriately energizing an associated Kerr cell inaccordance with the signal.

By employing a pair of cathode ray tube electronic switches of the character above described,

novel switches selecas the beam sweeps from-segment interval of.

the requisite connections for successively energiz ing the Kerr cells may be greatly minimized. This is accomplished, in accordance with one feature of the invention, by connecting the Kerr cells in successive multiple groups to successive segments of one cathode ray tube, and by further successively connecting such group to successive cathode raytube. so arranged, only one Kerr cell is connected between each different combination pair of segments in the first and second tubes respectively, a different cell foreach such combination, and that the total number of Kerr cells which may be thus uniquely connected, is equal to the product of the segments in the one cathode ray tube by those in theother. If each tube contains the same number of segments, as is preferred, the number of Kerr cells which may be thus uniquely connected, is equal to thesquare of the segments in one tube; or stated conversely, the number of segments required per tube is equal to the square root of the number of Kerr cells. It will be segments of the second It will be found that whenthe cells within each signal only seen/therefore, that a largenurnbe r'of Kerr cells I may be successively and-uniquelyenergized over a relatively few connections sealed through the glass containers of the Kerr cell; and, of the cathode ray tubes; the totalnumber .of connections amounting to twicethe square root-of the 7' number of Kerr cells. I For repeatedly energizing the Kerr cells in succession to effect line. scanning, the "cathode; ray beamsof the respective tubes areswept at;

Kerr cell connections, above ,stated-tfor each combination pair ofsegme'nts. In accordance with various modifications of the invention as described -hereinafter, the Kerr 7 cells may bedirectly connected-tethe cathode ray tube segment s, or may bev connected thereto through vacuum tube amplifiers, either individually energized orenergized from common battery sources as explained hereinafter.

With the system arranged as above outlined, each Kerr cell sunit will respond to, the impressed,

solongasthe cathode beamsbt fhe cathodetubes are simultaneously .incidentpn the pair of segments towhich such Kerr cell is connected. may be a matter of buta few millionths of. a second or usually even less. The energization of each Kerr cell, unit may be prolongedin accordance with a further aspect of the invention, byshunting each unit with a condensen-and resistor in parallel, With this arrangement, thecondenser charges up to the full signal strengththe instant thesignal voltage is impressed onits asspciatedKerr cells Thereafter and while the impressed signal is v passing on -to succeeding cell units, the condenser by slowly discharging through its shunt resistor, maintains the signal voltage across the Kerr cell. The time constantof each such unit is so adjusted as to retain the signal on each cell for. an interval approximating one linescan, while assuring, however, that the condenser will be fully discharged and the signal thus extinguished .in time for thenext signal energi zation. The invention is, of course, not limited to the use of Kerr cells as the light controlling elements. These may be replaced by or other'appropriate light valves on making the requisite, obvious circuit modification, The shunt condenser and resistor arrangement above described, is particularly applicable for adapting neon tubes to high speed scanning. ,As is well known, neon tubes alone are too sluggish spouse for this to be actuated by a signal im pressed thereon for but a few millionths of a onetube traverses all s eg-- ments thereof while the beam ofthe other tu-be mode of .connecting the Kerr cells to the segments-to provide the unique;

a row of neon tubes secon 7 in 'accordance'xifith the invention by shunting the same with a condenser and resistor selected I to retain the charge for approximately one line scan. The condenser, as stated, changes instantly to the full signal strength, while the refo wevr, such response can be received sistor holds the charge until the-tube .has time to respond.-'- with this" arrangement; therefore,

neon tubes may be employed for high speed televising as effectively as Kerr cells In the drawings: Fig. 1

or the like.

is a schematic layout of a complete te le vision receivingsystem in accordance with -,.one

modification of the invention, the optical system being shown in perspective and the electricalcir:

cuits diagrammatically. In this modification, in;

dividually energized vacuum tubes are interposed between the cathodfray tubes 'and the Kerr cells;

"a" fragmentary detail "of one of the" fthbsbfFiKgfl:

Fig. is "a diagr 'mmatic""showing'cf a row or a circuit diagram showing the requi- 'th'e' Figi-l layout for ener 'etail of one or-the e'ctly fromthe cathmittin'g-the vacuum 1 neon tubes, Kei-r cells or-the lika'employing-the V shuntcondenser i 'e'sisterfarrang'ement above described for holding'fthe sigrial-enrgization.

Referring to Fig. 1,*th eaboye' meiitioned multiple unit' Krr ecu, is shown at l,' and the "cathode'ra'y tube electronioswitchesiat 2 and 3-. Each: tube 2 3, comprises the usual hermetically sealed i successive multiple groups of -five.e ach, such as and 2|, Fig. 2, to successive segments H of the lowercatheode ray tube 3. The upper electrodes |4 within each multiple group 20, 2|, etc., are in turn successively connected to segments l0 ofthe ,upper cathode ray tube 2 over conductors-22, --23 and interposed vacuum tubes 24 conductors 231being'for this purpose sealed through the'glass container of the ,Kerr cell, and

. .;connected successively to the upper electrodes ineach multiple group 20, 2|, etc., in the man- ''-ner showna't 25, 26,'Fig. 2.- It will be observed l--that-withthismode of connection, only one Kerr cell .unit is connected between any segment l0 *ofth'e upper cathode ray tube 2 and any seg- -ment ll of.

posed vacuum tubes 24, I8;

the lower tube 3 through the interthat, moreover, there are twenty -flve different combinations by which segments and II may be thus paired; and that a different one of-the twenty-five Kerr cells is connected :between each different such pair of. segments l0 and 'l|.' -.As will be explained hereinafter, the manner in which simultaneous incidence of the cathode ray beams 8, 9 on any particularpairof segments IO, N, energizes the Kerr cell connected between such pair over the circuits traced, but assuming this to be so for the moment, it is further to be noted that if cathode ray beam 3 of tube :2 is caused to traverse segments l0 thereof-at five times the speed withwvhich beam 9 of tube 3 is caused to traverse segments thereof,;that the twentyfive celliunits in theKerrcell will be successively ancl'repeatedly energized. If,-u'rthermore, the cathode ray. beams 8. and 3 arexmodlllated in accordanceiwith. television signalsas they are thus z.swept acrossisegments HI and 'H, the Kerr cell glass container' 4,'5, the fiared'base 631 of which provides ascreen upon which the "cathode ray beam 8; 3 isincident. Disposed about'the screen onthe .interiorfof each tube,'-are the conductive segments, such'as Ill, 1 thj;number of which in each tulie'is determined were number of Kerr cells tobe enrgi'zedas above" explained.- In'the modification 'shownf and merely for purposes of illustration, each ments, whereby the cathode ray' 'tubes are adapted to successively energize the units of aKerr cell containing twenty-five cellunits.

The Kerr cell "I, in the modification shown, comprises'a rectangular glass time "contains five such segcontainer l2, filled with a liquid 13, such asfnitrobenzine, adapted when subjected toa voltagato polarizedlight; The container also houses an upper row.of twenty-five rectangular electrodes,"

rotate a beam of' such as M, insulated from one'another by mica or the like, and" a ljo'wer'row of fiv rectangular:

electrodes, such as |5, likewlse insulated from one another by mica or thelike, and spaced from the upper 'rowor'electrodes to provide a' linear light aperture or slot |6'therebetween,;each lower electrode, such as l5, spanningflve oi the upper electrodes as shown in perspective in Fig. 1 and diagrammatically in Figs. 2 and 3. 1

Sealed throughthe glass'container |2 oi the Kerr cell are five conductors H which are successively connected to the lower electrodes l5, conductors'l'l 'in turn'being linked, as explained hereinafter, through vacuum: tubes l8 individual thereto, and over conductors l9 segments ll of cathode ray tube lower Kerr cell electrode upper electrodes H, the connections l1,

3. Since each are tantamount to connecting the Kerr cells in to successive willbe likewise successively energized in accordance with said signals.

Considering now the precise manner in which the Kerrcells are successively energized by the cathode ray tubes in-accordance' with .received television signals, it will be -observed from the drawingsthat aside from the segments l0 and II, the cathode-ray tubes are generally of standard construction; The tubes are provided with the usual cathodes 30, 3|, grids 32, 33,-beam concentrating tubes .34, 34a, andvertical' and horizontal deflector plates 35,36 and3l, 38. The tube electrodes are energized in the usual manner from the potentiometers 33, 40 fed by batteries 4|, 42,

across which are shunted by-pass condensers 43,

For modulating the cathode ray beams 8, 9 in accordance with-television signals, and for simultaneously causing the same to traverse the segments 10, II in the manner above stated, modulated television and synchronizing frequency signals received'irom antenna 45'are fed through a demodulator 46, the output of which is connected in parallel to'a television signal frequency am- 'plifie'r 41, and a synchronizing frequency ampli- I5 spans five of the fier '48; The output of the signal frequency amplifier 41 is fed in parallel over conductors '49, 50 containing blocking condensers 5|, 52 respectively directly to grids 32, 33 of the cathode ray tubes 2, 3, and also through resistors 53, 54, and

through the'by-pass condensers 43, 44 to ground at 55, 56 respectively. Since resistors 53, 54 are connected tothe points on potentiometers 39, 40

adjacent the cathodes 30,-3|,- the'voltage drops across 'these' resistors which are traversed to groundat 55; 58'by the television frequency signalling currents; causes the necessary signal frequency voltages to be impressed between the grids and cathodes of the tubes-2, 3 for modulataccordance ing the cathode ray beams thereof in withr'eceived television signals.

The outputofthe synchronizing freduency'amtentiometer 58 connected between the grid and cathode of a dynatron oscillator this oscillator in step with the 59, for locking-1 1 incoming syn chronizing'signal, the oscillator beingadjustable to this end by variable condenser lifl. The output of oscillator 59 is impressed by'm'eans'of 62 between a? pair of" transformer windings 6 I conductors 63,54; across which is bridged a con--- nection containing a resistor 65- and condenser 66 m series; which connection is grounded at" 61- betweenthecondenser and resistor. =C'onduct'or y 63 extends to one of the horizontal deflector"- plates 38 of cathode ray tube '3,=and conductor 64 to one'of the vertical plates 35 thereon-{the opposite-verticaland horizontal deflector plates beinggroundedat 56 asshownp. The horizontal and vertical deflector plates are accordinglyem ergized in phasequadrature at the synchronizing frequency, due to the phase splitting action of resistor 65 and condenser 66-, and the ground re I57; The cathode ray'bea'm" ore, caused to repeatedly hereof at the synchronizparticular tube '21 circuits 10,11, to select which extends to one of the vertical deflectorplates and the second-of which extends to' one of the horizontal deflector plates 3 of the cathode ray tube 2, the remain i ing deflector plates of which are grounded at 553 Bridged between conductors 13, 14 is a'series connection containing a resistor -l5 and condenser 76, which connection is grounded at "between the resistor'and the condenser, therebyto'ener horizontal deflector plates gize the vertical and of tube 2 in phase quadrature, and at a frequency corresponding to the fifth harmonic of the synchronizing. frequency. In this way, the cathode ray beam 8 of tube 2 is caused to repeatedly traverse the segments I 0 thereof at five times the speed with which the cathode ray beam- 9 of tube 3 traverses segments ll" thereof, whereby the cell units of the Kerr cell tare successively energized in accordance with the received television signals, in the manner abovej now to be explained more in detail, 1 r

It will be observed that each of the'upper electrodes M of the Kerr cell is connected over a conductor 2 3 14 a the plates of tubes 24 extend to the positive ter-' minal of a battery 8!], the negative terminal 'of which is grounded. Likewise, it will be observed that each of the lower Kerr cell electrodes I5 is outlined "and to the jungrounded cathode of tube, connected to such conductor, and that all of F connected over a conductor l1 tothe plate of the associated vacuum tube l8, the cathodeof which is grounded at 8L] Therefore, the voltage ofbattery 80 will be impressed between the lower Kerr ,cell electrodes through paths of tubes grid voltages of the flow of plate current therein. Normally, however, each of tubes 24 is biased to cutoff by 18 and 24 in series, provided the upper and e pace.

these tubes are such as to permit the flow of plate current therein,

between a' difierent explained.

the grid biasing batteries and connected between the cathode and grid thru the secondary windin'g 'of an input transformer 83 ha'vin'g a separate primary winding. Likewise, each 'of tubes [Bis normally biased to cutoff-by the commonnegativeigrid biasing battery 84: connected to the grids; of each tube 18 resistors 85, battery 84 through the individual 7 being shunted to ground at the positive terminal with the by-p'ass condenser :86. Therefore, the

space paths of all of tubesl8'and 24 are normally" 1 open, to preventvoltage of battery "I 8 from being of'- the Kerr cell units.

impressed across any 7 Should, however, the'hegative grid bias on any one of tubes-'24 and any one of tubes ['8 be simultaneously reduced tosuch arr extent as to permit then the voltage of battery would be impressed across the particular one of the Kerr cell unit havingits upper electrode connectedtothe "cathode of the and its lower electrode connected to plate of-"the particular tube*l;8 inquestion. Simultaneous bias on'but one "tube cause voltage-'80 to Kerr c'euunit, the 7 mg unaffected. This resultsfrom the mode of connecting'the up 'r andlower Kerr cell electrodes to' the conductors l1 and 23 above 'debe impressed across but one scribed, whereby each Krr'cell unitisconnected combination pair of tubes 24 and I8 corresponding-{tomeconnection thereof through the tubes to a different combination'pair of cathoderay tube segments 'l li and as above Simultaneous reduction" and 18, such as" to impress avariabl fraction of-voltage 80 across-the Kerr cell unit sucjcessively in accordance with received television signals; Y 'is brought about by the cathode ray beams 8', 9

of tubes 2, 3,'modu1ated-in accordance with the received televisionsignals, as explained, andsweeping "across the conductive segments 10, H" I I the relative speeds above :;des'cribed; Tothisend, the cathode ray tubes in the I manner and at 2,3 are so constructed, and the velocity of the segments III, II so adjusted by battery'l l, asto produce's'econdary electronic emission from these segments up'on'inc'idence of the beam thereon.

For. collecting these" secondarily emitted electrons, the flared necks adjacent the screens't, 1 of the glass tube receptacles 4, '5are provided on their interior surfaces with conductive coatings'of graphite or the likeas shown at '81 in Figs. land in. The secondary emission thus produced ingtube 2 is utilized to reduce the nega.' tive bias; on tubes W 7 between 'theirassociated conductors 22' and the negative terminal of a alt -89; nccordingly as the cathode ray' beam 8 sweeps across any ondary emission therefrom will produce a flow of electronsQi. e. current from batteryfllth'rough the primary winding of'trans'former 83 connected to the segment'in 22f thereto, thence through the space within the tube to the conductive interior 8!, returning thence to battery 8! through ground 89 and the 82 individual thereto,

reduction of the negative" flyand butone' tube l8-to' 'pe'rinit the flow of spa'oeilcurrenttherein would 1 balalhce of the 'uh'itsirem'ain v ofthe negative grid biases on difierent combination pairsfof tubes 24 25 successively by connect-v ing-th'e primary windings of their respective input transformers "83,

given segment I 0, the sec question, and over conductor groundedbattery terminal. .The resulting flow of current in the primary of transformer 83 will induce avoltage in of such polarityv andmagnitudeas momentarily todecrease the negativebias The .actiongwith respect to cathode ray tube 3 is-.qui te similar; 1;During1ncidence;of the cathon the; grid of; the associated tube 24, sufiicientlyto render its. space path conductive and proportional to the,

the; secondary thereof battery source. In 2, the plates of the vacuum tubes I8 are connected as before over con- ,ductors IIto the lower electrodes I5 of the Kerry cells, the: upper electrodes of which are connect: edin multiplegroups as previously to conductors 23, which conductors in this instance, however, extend to the plates respectively of tubes 24, the

cathodes of which are directly grounded as shown at I20. Conductors 23 are also connected through the resistors II8 to the positive terminal of a battery! grounded at its negative terminal.

The segments III of cathode ray tube 2 are con- ,nectedrespectivelyover conductors HI and I22 ode ray beam 9; on any segment .I,I,, secondary emission occurs ,to produ cega tlo w of current from the common grid biasing battery 84 through the grid resistor 85 of tube;18, connected to thesegment II on-twhichgi he-vcathode,beam is incident, and over, conductor I 9 segmentdn the space within; the. tubeto the conductiveinterior thence to; ground .at ill, returningtobattery. 84 through its grounded-positiveterminal. A- booster battery, with-the negative terminal grounded maybe inserted on: ground leadigel if ;necessary,

The resuljtingvoltage drop across grid resistor thereto, thenceirom this :81,.as 'shown .at 90. in Fig. 1a,,

85 by using up;,some ,of the voltage of battery 84, reduces the negative .bias on, the associated grid of tube .I8 to such anextent that its space path is renderedconductive in proportion to the television signal atthatiihstantf This action is a of course grepeatejdifor. tubes 18 successively as the cathode ray;beamfsweeps across segments II.

Therefore, the simultaneous sweeping of the television modulated cathode ray. beams 8 and 9 across segments In" andJ l the one at five times thespeed m 80 ,to be successively impressedacrossthe Kerr cell units and, in proportion to V the television signals. v

To render theabove describedenergization ofthe.Kerr cellsefiective forscanning, an opt iof the other, causesvoltage from source. 7

cal system isassociated therewith, comprising, an I electric bulb I08 having a rectilinear filament IM 7 energized by battery I02, the illumination from which is. 1 condens u Ill3, and directed through an interposed polaroid polarizer; I0 4 onto the rectilinear slot-I6 of the Kerr cell, behindwhich is positioned a polaroid analyzer I05 and a rotatable. polyhedral mirror drum I06, worm driven by motor I01, the mirror drum being arranged to, deflect the emergent light beam, onto ,a defiecto r llttt, whereby the d'by a cylindrical lens v from the segments III. The segments II of cath-.

ode ray tube 3.are connected, as previously, over conductors I8 to the grids respectively of tubes I8, through blocking condensers I25, the control grids. also being connected, as before, through the individual resistors 85 to the common negative grid biasing potential source, comprising the negative biasing battery andassociated potentiometer I21 grounded at the positive terminal. Cathode ray tube 3 is the same as in Fig. 1, namely, of the secondary emission type as indicated at 81. For utilizing this secondary emission in the manner to I28 containing resistors I29, extend from the cathode ray tube segments II respectively, to the negative terminal of a common battery I30 grounded at its positive terminal.

In the operation of this system, tubes I8 are normally biased to cutofi by the potentials supplied to the grids thereof from source I21, so that the plate circuits of these two are normally open. The grid potentials of tubes 24 on the other hand, are so adjusted by source I25 operating through resistors I24, as normally to permit a sufflcient flow of plate current in these tubes from their grounded cathodes and over conductors 23 and through resistors H8 and a common battery II9 back to ground, that sub.-

image producedv maybe viewed at I89. The polaroid polarizerfland analyzer are each arranged,

with theirpolarizing axes at 45 degrees to the Kerr cell slot, and at 90 degrees to each other, so that in the absence otreceived television signals, no light is incident, on the mirror drum I06. The mirror drum isrotated at such speed as to provide frame or picture scanning, as line scanning is effected by the Kerrcells. Line .scanning bylthe above cells of course accomplished by rotation of the polarized light incident therea on to permit passage through the analyzer in accordance withthe television signal, as these cells are successivelyenergized in the manner above described.

In the modification of Fig. l, the cathodes of tubes 24 can not be grounded, otherwise battery 80 will be rendered ineffective toimpress a voltage on the Kerr cells. For this reason, .each of tubes 24 requires individual cathode and grid batteries. Fig. 2 shows an arrangement whereby these tubes may be energized from a common stantially the entire voltage of battery H9 is dissipated across the resistors I I8. Normally, therefore, no voltage is'impressed between the upper and lower electrodes I4 and I5 0f the Kerr cell units, since the upper electrodes are normally substantially ground potential, while the lower electrodes are connected to the open plate circuits of tubes I8. 7

When, however, the cathode ray beam 8 of tube 2 is incident on a segment I0 thereof, the electronstream comprising the cathode ray beam flows through the segment III on which it is incident, over conductor I2I connected thereto and .through the associated resistor I24 to ground thorugh the grid biasing source I25, re-' proportion to the intensity of the cathode ray beam 8 at that instant. This reduces the voltage drop across the corresponding resistor II8 in the conductor 23 connected to the plate of turn increases the tube 24 in question, which in voltage impressed from source II! on the upper be described, conductors the.negative potential on uum tubes, such as to ring Kerr cell electrode I4 connected to this conductor 23. 7

During the existence of this condition, the cathode ray beam 9 of tube 3 will also be incident on one of its conductive segments II. The cathode ray beam of this tube is of such intensity, as explained, as to produce secondary emission from the segment II on which it is incident. In consequence of this secondary emission, a flow of electronic current will be established in the circuit traced frombattery I30 and through re,- sistor I 29 and over conductor I28 connected to the segment II in question, thence in the space within the tube through segment, II to the conductive inner wall 81 to ground at 90, returning thence to the grounded positive terminal of battery I30. The voltage drop in resistor I29 due to this current flow, will momentarily reduce the negative biasing voltage on the grid of associated tube I8, to such an extent as to render the plate circuit thereof conductive in proportion to the received television signal. Voltage from source II9 will therefore be impressed between the particular upper and lower electrodes I4 and I5, which are connected between the pair of tubes 24 and I8 that have been energized in the manner above described. As the cathode ray beam 8 of tube 2 sweeps across the segments I thereof at five times the speed'at which beam 9 of tube 3 sweeps across segments II thereof, tubes 24 and'I8 will be successively energized as above described, to permit battery I I9 to impress a voltage across the Kerr cells successively,

which varies in accordance with television sig-' nals.

Fig. 3 shows a modification of the invention which does not require the interposition of vac- 24 and I8, between the Kerr cell and the cathode ray tubes 3 and 3 respectively. In this case, each of the screens 6, I of tubes 2, 3 has a ring of insulated conductive segments III, II disposed thereabout as previously, and in addition has disposed close to the segments, a continuous ring I3I, I32 of conductive material. In tube 2, the cathode ray beam traverses the conductive segments III, while in tube 3, the cathode ray beam 9 traverses the continuous ring I32. The upper and lower Kerr cell electrodes I4 and I are connected over conductors I33 and I34 to segments III and II respectively, in the same manner as in Fig. 1 ex cept'for omission of the vacuum tubes. Each of the cathode ray tubes 2 and 3 is so constructed and arranged, in the manner above described, that the cathode ray beam thereof produces secondary electron emission from the, conductive members on which it is incident. This secondary emission is utilized to energize the Kerr cell units, by connecting the positive terminal of a battery I35 to ring I32 of tube 3, this battery being grounded at its negative terminal as shown; and by grounding ring I 3| of tube-2 as shown at I36.

. returning to the grounded battery I35.

' ance with the points'of incidence of said cathode In the operation of this system, as the cathode ray beam 8 traverses segments I 0, it will produce secondary emission from the segment on which it is incident at any given instant. Likewise, as the cathode ray beam 9 of tube 3 traverses ring I32 thereof, it will continuously produce secondary emission at the point of incidence. These secondary emissions will permit displacement current to flow from battery I35 I32, thence from this ring by virtue of the secondary emission to the segment II which is adjacent the point of incidence of the cathlower Kerr cell electrode I5 connected thereto,

thence to the upper Kerr cell electrode connected over conductor I 33 to the particular segment III of the cathode ray tube 2 incident at that instant, thence ,to ring I3I by virtue of the secondary emission to ground at I36 negative terminal of In this way, as the cathode ray beams 8 and 9 continue to rotate, a voltage varying in accordance with the television signals will be impressed on the Kerr cells successively to effect scanning. Fig. 4 illustrates at I31 the manner in which the secondary emission resulting from incidence of cathode ray'beam 8 of a segment II of tube sion, the electrons resulting from which are drawn to the ring I3! I35 and ground I36 over As above stated, the

the circuits above traced.

signal energizations of Kerr cells, neon tubes, or other light control elements employed may be retained following each energization, by shunting each element with a condenser and resistor suitably chosen to provide a desired time constant. Fig. 5 shows this arrangement diagrammatically,'wherein a row of Kerr cells, neon tubes, or ments for effecting line scanning is shown at I40 in part. Shunted across each element is a condenser I 4| and a resistor I42 for purposes above stated. Each unit is provided with input leads I43, I44 across which the signal is impressed.

I claim:

1. In a television receiving system: a pair of cathode ray tubes each having an insulating screen containing a conductive ring and spaced conductive segments disposed therealong, a plurality of electrically actuated translating devices, each connected between a segment of one tube and a segment of the other, a difierentcom bination pair of such segments for each device, means for causing the cathode beam of one tube to traverse the segments thereof and the cathode beam of the other tube to traverse the ring thereof, said beams producing secondary emission from said segments and ring respectively, and a source of voltage connected between said rings for selectively actuating said devices in accordbeams on said segments and ring respectively. 2. In a television receiving system: a pair of of and the cathode beam of the other tube to'" traverse the ringthereof, said beams producing secondary emission from saidsegments and ring WILLIAM H. PECK on which beam 8, is

2' produces secondary emisby the action of batterylight controlling elev actuated light controlling I pair of such segments for' 

